Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net income (loss) attributable to Adient	$ (54)	$ 150
Denominator:
Shares outstanding (in shares)	94.6	94.0
Effect of dilutive securities (in shares)	0.0	0.8
Diluted shares (in shares)	94.6	94.8
Earnings (loss) per share:
Basic (in dollars per share)	$ (0.57)	$ 1.60
Diluted (in dollars per share)	$ (0.57)	$ 1.58